diff --git a/ext/standard/filters.c b/ext/standard/filters.c
index 12166a8cc65..1b5a991be25 100644
--- a/ext/standard/filters.c
+++ b/ext/standard/filters.c
@@ -1507,6 +1507,8 @@ static php_stream_filter_status_t strfilter_convert_filter(
 		if (out_buf_size - ocnt > 0) {
 			new_bucket = php_stream_bucket_new(stream, out_buf, (out_buf_size - ocnt), 1, inst->persistent TSRMLS_CC);
 			php_stream_bucket_append(buckets_out, new_bucket TSRMLS_CC);
+		} else {
+			pefree(out_buf, inst->persistent);
 		}
 	} else {
 		while (buckets_in->head != NULL) {